M. Tender

Study on prevention implementation in tunnels construction: Marao Tunnel's (Portugal) singularities

DOI: 10.7764/RDLC.16.2.262 The investment in tunneling shows an worldwide expansion trend. Reduction of risks, as part of the financial strategy of the stakeholders, has been the focus of several research studies. This paper aims to describe the construction risk prevention, in terms of occupational accidents and diseases, of the 2nd phase of the Marao Tunnel (Portugal) – the longest roadway tunnel in the Iberian Peninsula excavated with Sequential Method -with the particularity of the works being interrupted, leaving the tunnel only with primary lining for three years. The methodology is based in: 1) identification, by literature review, of most typical preventive measures and assessement of their applicability in the case study; 2) description of new preventive approaches. The paper will start with a history of work accidents, followed by the case study and, finally, it will delve into the preventive measures applied, as well as the new approaches, such as over-runs, falling blocks and risks associated with the suspension of works. Measures identified in literature were implemented and their validity was assessed. New approaches provided an safer and quickest way to work. This study is relevant to future tunnelling sites, since it is a good example of risk management using new approaches.

Risk evaluation in tunneling excavation methods

Risk management is of paramount importance for the success of tunneling works and it is linked to the main excavation methods used: the Conventional Excavation Method (CEM) and the Tunnel Boring Machine Method (TBM). Considering the importance of the “Safety and Health” criterion for the choice of the excavation method, the fact that this criterion is usually mostly focused on the structural component, and taking in account that there is no research showing the advantages of one of the methods over the other, this research intends to conduct a comparative risk analysis between both methods, taking into consideration the different constraints that might appear. In order for this comparison to hold true, a risk evaluation is presented, analysing 12 risks and 4 risk factors in 3 phases, so that the impact of the different variables can really be appraised. This research is made in a scenario of the construction of a 3.5 km-long tunnel in a non-urban area, with an unproblematic rock mass. The final result will be a detailed analysis of the influence of “Safety and Health” criteria, useful for both the technical and the scientific community, something that has never been done before.

The role of underground construction for the mobility, quality of life and economic and social sustainability of urban regions

Tunnelling has been used for several purposes for thousands of years. In the coming years the worlds population will increase in the urban areas. So, the urban centres will have to adapt, in order to guarantee that their future population will have the necessary and sustainable growth. Due to the constraints for surface construction, also connected to environmental issues, this population growth will imply a greater use of the underground. With this optimal growth, the population of the cities will have better mobility, quality of life, and economic and social sustainability. In a first phase, this report will present a historic approach to tunnelling and its foreseeable future. Afterwards, we will present some considerations on the three factors which tunnelling impacts: mobility, quality of life and social sustainability. As a case study, we will analyse the 2nd phase of the construction of the Marão Tunnel (TDM) – the longest ever built in the Iberian Peninsula– and describe the options made regarding each of those factors. In this case study, the options implemented made it possible to successfully execute the works. For the industry, this work is important because it describes a successful management of the aspects under analysis.